Self-healing and tough hydrogels with physically cross-linked triple networks based on Agar/PVA/Graphene.

The aim of this work was to prepare polyvinyl alcohol (PVA)/Agar/Graphene nanocomposite hydrogels through a one-pot and green solution mixing method using water as solvent. Herein a novel strategy for designing stiff, tough and self-healing triple network (TN) hydrogels was proposed. The prepared TN hydrogels composed of strong Agar polysaccharide as the first network, tough PVA biopolymer gel as the second network, and graphene nanoplatelets as the third network. Interestingly, similar to natural biomaterials, all of the networks of the nanocomposite hydrogel were physically cross-linked via dynamic hydrogen bonding associations, i.e. Agar helix bundles, PVA crystallites and polymer chain physisorption on graphene. Therefore, the prepared hydrogels demonstrated simultaneous high strength, toughness, and autonomous self-healing within a short time of 10min, which is rare in the literature. The developed hydrogels can be a promising material in many biomedical applications, such as scaffolds, cartilages, tendons and muscles.